Case number:	184
Age:	70
Clinical presentation:	Postmenopausal woman with average risk of developing breast cancer presented with a left breast lump. Examination revealed a hard lump in the outer quadrant of the left breast.

Mammography:

Breast composition:	ACR category a (the breasts are almost entirely fatty)
Mammography features:

‣ Location of the lesion:	Left breast, upper outer quadrant at 12–2 o’clock, anterior and middle thirds
‣ Mass:
• Number:	None
• Size:	None
• Shape:	None
• Margins:	None
• Density:	None
‣ Calcifications:
• Typically benign:	None
• Suspicious:	Fine pleomorphic microcalcifications in segmental distribution and in clusters and in linear branching pattern
• Distribution:	None
‣ Architectural distortion:	None
‣ Asymmetry:	Present
‣ Intramammary node:	None
‣ Skin lesion:	None
‣ Solitary dilated duct:	None
‣ Associated features:	Skin thickening

Ultrasound:

Ultrasound features: Left breast, upper outer quadrant at 12–2 o’clock

‣ Mass
• Location:	Left breast, upper outer quadrant at 12–2 o’clock
• Number:	Multiple small
• Size:	< 1 cm
• Shape:	Irregular
• Orientation:	Not parallel
• Margins:	Indistinct and angular
• Echo pattern:	Heteroechoic
• Posterior features:	No posterior features
‣ Calcifications:	Intraductal microcalcifications
‣ Associated features:	Axillary lymphadenopathy
‣ Special cases:	Solitary dilated duct

BI-RADS:

BI-RADS Category: 5 (highly suggestive of malignancy)

Further assessment:

Further assessment advised: Referral for cytology

Cytology:

Cytology features:

‣ Type of sample:	FNAC
‣ Site of biopsy:
• Laterality:	Left
• Quadrant:	Upper outer quadrant
• Localization technique:	Palpation
• Nature of aspirate:	Whitish, blood tinged
‣ Cytological description:	Smears are very cellular and show dyscohesive clusters of pleomorphic malignant cells
‣ Reporting category:	Malignant
‣ Diagnosis:	Carcinoma breast
‣ Comments:	None

Histopathology:

MRM

Histopathology features:

‣ Specimen type:	MRM
‣ Laterality:	Left
‣ Macroscopy:	Left MRM specimen (24.0 × 16.0 × 7.5 cm) with skin flap (11.0 × 6.5 cm). On serial sectioning, a firm greyish white area (6.0 × 3.0 × 3.0 cm) is seen in the upper outer quadrant and extending to the lower outer quadrant. A second firm area (1.5 × 1.0 × 1.0 cm) is seen 3 cm medial to the first firm area in the upper inner quadrant. The intervening breast parenchyma shows interspersed whitish calcified areas
‣ Histological type:	Microinvasive breast carcinoma
‣ Histological grade:	Grade 2 (3 + 2 + 2 = 7)
‣ Mitosis:	12
‣ Maximum invasive tumour size:	Six foci of microinvasive breast carcinoma; all < 0.1 cm in greatest dimension
‣ Lymph node status:	0/10
‣ Peritumoural lymphovascular invasion:	Absent
‣ DCIS/EIC:	DCIS of cribriform, comedocarcinoma, and solid type, high grade with necrosis in both the firm areas seen grossly. EIC present. Multiple foci of DCIS extending over 6 cm in greatest dimension
‣ Margins:	Free of tumour
‣ Pathological stage:	pT1miNo
‣ Biomarkers:	ER positive, PR positive, and HER2 negative
‣ Comments:	The adjacent breast also shows lobular mastitis with a chronic inflammatory infiltrate

Case summary:

Postmenopausal woman presented with a left breast lump. Diagnosed as solitary dilated duct with fine pleomorphic microcalcifications in segmental distribution and in clusters and in linear branching pattern, BI-RADS 5 on imaging, as breast carcinoma on cytology, and as microinvasive breast carcinoma pT1miN0 with EIC on histopathology.

Learning points:

EIC is defined by the following criteria:

> 25% of the area within the invasive carcinoma is DCIS and DCIS is also present outside the area of invasive carcinoma in the surrounding breast parenchyma.
There is extensive DCIS associated with a small (1 cm or less) invasive carcinoma. This case fulfils this second criterion.